Modification of drying oils



United States Patent() MODIFICATION OF DRYING OILS Herman S. Bloch,Chicago, Ill., assiguor to Universal Oil Products Company, Chicago,Ill., a corporation of Delaware No Drawing. Original applicationFebruary 18, 1948, Serial No. 9,332, now Patent No. 2,611,788, datedSeptember 23, 1952. Divided and this application August 20, 1952, SerialNo. 305,519

5 Claims. (Cl. 260-407) This application is a division of my copendingapplication Serial Number 9,332, filed February 18, 1948, now Patent No.2,611,788, September 23, 195 2.

This invention relates to a process for modifying the physicalproperties and certain other characteristic qualities of unsaturateddrying oils selected from either the fatty acid ester or synthetichydrocarbon drying oils, especially those containing conjugated olefinicunsaturation. More specifically,the invention concerns a method ofaltering the molecular structure and simultaneously, the physical anddrying properties of unsaturated drying oils by chemically condensingthe drying oil with an olefinic hydrocarbon reactant which therebyreduces the number of olefinic double bonds present in the drying oilreactant.

One of the beneficial results obtainable by the application of thepresent treatment to drying oils of either the unsaturated fatty acidester or the unsaturated synthetic hydrocarbon types is the reduction ofthe total unsaturation of said oils, particularly of their conjugatedunsaturation. The present treatment is believed to introduce suchchanges in the molecular structure of the drying oil that the ability ofthe oil to undergo polymerization and oxidation on exposure toatmospheric oxygen is affected to some extent, although not removedentirely. Observation has shown that in those instances in which theunmodified or raw drying oil on exposure in thin films to atmosphericoxygen forms a hard brittle layer of dried oil which easily checks andhas little abrasion resistance, as in the case of hydrocarbon dryingoils, modification of the oil by means of the present process forms aproduct which when exposed in thin films to atmospheric oxygen, forms aharder, tougher protective coating and provides a highly desirablecomponent in the formulation of paints, varnishes and other protectivecoating compositions. In the treatment, therefore, the drying oil losesits original undesirable characteristics associated with its highlyunsaturated character and low molecular weight to form a modified dryingoil having its film-forming properties and its quality in relation toits use in protective coatings thereby enhanced.

Other objects and advantages obtained by the application of the presentprocess will be hereinafter described with reference to the particulardrying oil charging stocks amenable to the present treatment.

In accordance with one of its embodiments, the present inventioncomprises a process for modifying a synthetic hydrocarbon drying oilcomprising'a mixture of hydrocarbon conjunct polymers containingpolyolefinic, cyclic hydrocarbons having conjugated as well asnonconjugated unsaturation recovered from a catalyst-hydrocarbon sludgeformed in a conjunct polymerization reaction wherein said hydrocarbondrying oil is reacted with an olefinic hydrocarbon at condensationreaction conditions until the desired degree of alteration of the dryingoil is effected as evidenced by the reduction of its maleic anhydridevalue.

Another embodiment of the present invention relates to a process formodifying the drying properties of tung J 2,719,164 Patented Sept. 27,1955 oil which in its unmodified state dries on exposure to atmosphericoxygen at a rapid rate resulting in a dried film having a cloudy orfrosted appearance, said process comprising reacting said tung oil withethylene at a superatmospheric pressure and at a temperature of fromabout 50 to about 300 C. to thereby reduce the number of conjugatedolefinic double bonds present in the fatty acid esters comprising saiddrying oil and to increase the molecular weight thereof accordingly.

It has been recognized and applied in the production of protectivecoating materials that bodying the drying oil by the application of heatthereto effects a desired change in the drying properties of the oil forprotective and decorative coating purposes. In the bodying reaction, theunsaturated drying oil supposedly undergoes a type of polymerizationinvolving the unsaturated olefinic linkages present in the drying oiland results in a reduction of the total unsaturation of the oil andprovides a product having a greater viscosity and better dryingqualities. Although the present process may be operated entirely on athermal basis in which the drying oil or mixture of drying oils may beheated to initiate the reaction and thus promote a partial heat-bodyingreaction, it is believed that the relatively low temperatures at whichthe present reaction has been observed to proceed (as low asapproximately 50 C.) would preclude any extensive polymerization of thedrying oil component present in the reaction mixture. Rather, thereaction mechanism involved in the present process is considered to be acombination copolymerization and/ or a condensation of the olefinichydrocarbon reactant with the drying oil or mixture of drying oilscharged into the process. The molecular weight, for example, of themodified drying oil is increased as a result of the present treatment,and perhaps the most significant changes as related to the dryingproperties of the oil, is that the modified oil has a lower maleicanhydride value indicaing that the conjugated unsaturation has beenreduced during the treatment. The observed physical effects of theconversion is a reduced drying rate of the modified oil and adisplacement of the tendency of the oil to become frosted or cloudy ondrying, as in the case of such rapid drying oils as tung, oiticica anddehydrated castor oil. Furthermore, the modified oils do not show thesame tendency to yellow and undergo pronounced coloring effects whenaged following the drying. thereof, as shown by the unmodified oil,especially in the case of the fatty acid ester drying oils, notedparticularly in such glycerides as isomerized linseed oil. Hydrocarbondrying oils such as those recovered from catalyst-hydrocarbon sludgesformed in conjunct polymerization reactions and containing hydrocarbonshaving a cyclic, polyolefinic structure in which a large percentage ofthe olefinic double bonds are conjugated, as hereinafter morespecifically characterized, are also improved by application of thepresent treatment thereto. The physical improvement in the latter typeof drying oil or a cobodied mixture of the same with the fatty acidglyceride drying oil is indicated by the pronounced reduction in theembrittlement factor inherent in the unmodified drying oils whenair-dried. In contrast, the modified drying oil under the same dryingconditions forms a dried film which is tougher, more resistant toabrasion and possesses significantly greater weather resistance than thebrittle films formed upon drying the raw or unmodified drying oil. Thelatter change in properties is especially valuable in increasing theutility of the drying oil in the formulation of paint and varnishcompositions where toughness and abrasion resistance of the dried filmare especially important characteristics in nearly all applications ofthe drying oil.

An individual drying oil or a mixture of the various types of dryingoils herein specified may also be sub:

ice

jected to an intense modifying treatment with the olefinic reactantprovided herein to convert the same into oils of the non-drying typewhich are useful, for example, as lubricating oil additives and asplasticizers, some of which may be vulcanized, for incorporation intoresins, elastomers and the like.

The primary starting material which may be subjected to modification bymeans of the present process and herein specified as a drying oilincludes generally the poly-unsaturated fatty acids and their esters aswell as certain types of unsaturated relatively high molecular weighthydrocarbons hereinafter identified and described in greater detail. Thefatty acid ester type of drying oils occurs naturally as fatty acidglycerides, although these may be modified for the purposes of thepresent process by replacing the glyceride ester linkage with othertypes of alcohols, such as ethanol, polyhydroxy glycols such as ethyleneglycol, pentaerythritol, sorbitol, and the like, or alkanol aminesrepresented for example, by the mono and poly ethanol amines. Includedamong the fatty acid oils utilizable in the present process are thedrying and semi-drying classes containing conjugated and/ornon-conjugated olefinic double bonds. Of these, tung oil, linseed oil(either raw or boiled linseed oil), dehydrated castor oil, oiticica oil,perilla oil, olive oil, poppy seed oil, coconut oil, soy bean oil, hempseed oil, poppy seed oil, safliower oil, walnut oil, etc. arerepresentative oils of the glyceride ester type utilizable herein. Theprocess is of greatest utility, however, with oils which have conjugatedunsaturation or which develop conjugation upon heating. The fatty acidesters contained in the above oils may be hydrolyzed and the fatty acidsliberated by hydrolysis may be recovered and utilized herein.Oil-modified alkyd resins, oil-modified phenolics, or other drying-oilmodified resinous materials may likewise be treated as herein described,or such oil-modified resins may be prepared from drying oils ordrying-oil fatty acids previously treated by the present process.

The drying oils herein specified as the hydrocarbon type drying oilscomprise hydrocarbons of unsaturated structure generally of relativelyhigh molecular weight, above about 250, and usually of cyclic structurecontaining conjugated as well as non-conjugated unsaturation.Hydrocarbons of the above type having drying oil properties may beprepared in any suitable manner known to the art or may be derived fromvarious natural sources, as in the case of certain terpene fractions.One of the preferred sources of the hydrocarbon type of drying oil whichis especially suitable as the drying oil reactant in the presentprocess, are the catalyst-hydrocarbon sludges recovered from certainhydrocarbon conversion processes utilizing catalysts capable of causingconjunct polymerization between the hydrocarbon reactants charged to theconversion process. Typical of the catalysts capable of causing conjunctpolymerization reactions are the various Friedel-Crafts metal halidecatalysts, such as aluminum chloride and aluminum bromide and certainmembers of the acid type catalysts, such as concentrated sulfuric acid,substantially anhydrous hydrogen fluoride and borontrifiuoride as wellas others generally known to the art. The above catalysts when contactedwith a reactive, generally non-aromatic hydrocarbon, such as a monoorpolyolefin containing at least 3 carbon atoms per molecule or a branchedchain paraffin at reaction conditions favorable to the formation ofconjunct polymers, produce a catalyst-hydrocarbon containing sludge as adistinct reaction product of the process. Conjunct polymerization occursin the mixture of catalysts and hydrocarbons by virtue of simultaneouspolymerization, cyclization, and hydrogen transfer reactions between thehydrocarbons to form relatively saturated hydrocarbons as one reactionproduct and an accompanying product comprising high molecular weightcyclic compounds generally referred to in the art as conjunct polymers,containing from about 2 to about 4 double bonds per molecule 'inconjugated as well as nonconjugated relationship to each other. Theconjunct polymers, usually having a molecular weight of from about 250to about 450 and in some cases up to about 1000 become bound by weakchemical bonds to the conjunct polymerization catalyst to form thesludge hereinabove referred to and may be released therefrom by heatingthe sludge, by hydrolyzing the chemical bonds, as for example by addingthe sludge to water or a dilute caustic, or they may be recovered byextraction or displacement with a solvent or a more reactive material.It is not the purpose nor is it essential here to describe in detail themethods of producing sludge or of recovering the hydrocarbon type ofdrying oil therefrom; but a description of the process relative to useof substantially anhydrous hydrogen fluoride as conjunct polymerizationcatalyst (which forms a conjunct polymer hydrocarbon product having amaximum in conjugated unsaturation as compared to other conjunctpolymerization catalysts and a product which on observation possessesmany of the most desirable characteristics of a drying oil) will bebriefly referred to in the examples hereinafter specified. The dryingoil starting material may also comprise a cobodied mixture of anunsaturated fatty acid ester and an unsaturated hydrocarbon drying oilpreferably cobodied prior to the present treatment. The cobodyingreaction may be effected by intimately mixing the drying oils andheating the mixture to a temperature of from about 250 to about 350 C.for a period of time generally from about 1 to about 6 hours, or untilthe viscosity approaches the desired value. The cobodying reaction,however, should not be continued to the point where no furtherunsaturation remains in the drying oils since the latter characteristicsare essential to the present treatment and to the desired modificationthereof. Cobodying may also be effected in the presence of certaincatalytic agentssuch as acid-acting substances, typical of which are themineral acids, preferably phosphoric acid, the acidic silica-aluminacomposites or a solid phosphoric acid catalyst formed by calcining asiliceous adsorbent such as kieselguhr impregnated with a suitablephosphoric acid. The drying oils, either individually or a cobodiedmixture thereof may be steam or air blown prior to utilization in thepresent process to provide a drying oil containing a higher degree ofunsaturation and particularly of conjugated unsaturation.

The modifying reactant herein specified as an olefinic hydrocarbon whichundergoes condensation and/or copolymerization with the drying oilreactant to yield a modified drying oil is preferably a mono-olefincontaining fewer than about 8 carbon atoms per molecule, although highermolecular weight olefins may also be utilized when the reactionconditions are selected to obtain the desired condensation and/ orcopolymerization elfects between the reactants. Vinyl aromatics, such asstyrene, likewise copolymerize with drying oils of the type described,but the copolymers thereby formed are different in properties from themodified drying oils herein described. Of the utilizable non-aromaticmono-olefins, including iso-olefins, such as isobutylene, cycloolefins,such as cyclohexene, etc., ethylene is the preferred reactant because ofthe relative ease with which the drying oil undergoes modification inthe presence of said olefin as compared to olefinic hydrocarbons ofhigher molecular weight. In the presence of ethylene, for example, thereaction proceeds at comparatively low temperature conditions, whereasfor the utilization of higher molecular olefins, such as pentene-l,generally more severe conditions such as higher temperatures or longerreaction times are required to obtain the optimum degree ofmodification.

The condensation and/or copolymerization of an unsaturated drying oilwith a mono-olefin hydrocarbon to form a modified drying oil product ofincreased molecular weight and generally containing fewer conjugatedand/or isolated unsaturated bonds is effected at temperatures of fromabout 50 to about 300 C., preferably at temperatures of from about 100to about 200 C., and at pressure suflicient to maintain a liquid phase.Catalysts, such as, for example, materials of the quinone type such ashydroquinone or anthraquinone, may be introduced into the reactionmixture to initiate or accelerate the reactions involved in the presentprocess, usually in amounts of from about 0.1 to about 2% by weight ofthe reaction mixture. Catalysts may be especially eflective in obtainingan accelerated reaction rate in the case of certain olefins,particularly the straight chain and high molecular weight types. It isto be emphasized, however, that the reaction may be initiated in theentire absence of any recognized catalytic materials when properreaction conditions are selected.

Another type of catalyst particularly useful in the present process isthe class of catalysts referred to as peroxides, such as di-t-butylperoxide, benzoyl peroxide and t-butyl perbenzoate. When catalysts areutilized in the reaction, the catalyst may be allowed to remain in theproduct if desired or the product may be washed or contacted withsolvents such as water or a suitable organic solvent to extract thecatalyst therefrom. When utilizing the low molecular weight olefins, forexample, those containing fewer than about 5 carbon atoms per molecule,as the modifying reactant, the reaction temperature may be maintained atrelatively low temperatures of from about 50 to about 140 C. and usuallya catalyst is not necessary. Depending upon the degree of condensationand/ or copolymerization desired, low temperatures within the aboveoperable range may be maintained, although the extent of the reactionand the fluidity (that is the viscosity) of the resulting product may bedependent upon the reaction time, the presence or absence of a catalyst,and the reactivity of the starting materials. A drying oil, for example,containing a highly conjugated system of double bonds and/ or an olefinof low molecular weight generally react more readily than compounds notso characterized. The reaction rate may be further modified bydissolving the reactants in a suitable solvent such as an aliphaticsaturated hydrocarbon of preferably low molecular weight which may bereadily vaporized from the product following the reaction. Typical ofthe latter are such low-boiling hydrocarbons as propane, butane andpentane or their corresponding halogenated analogs, such as chloroform,carbon tetrachloride, etc.

The reaction involved in the present process is usually substantiallycomplete at reaction periods less than about 8 hours, depending upon thetype of product desired and the degree of modification of the originaldrying oil. The reaction may be conducted at relatively lowtemperatures, for example below about 130 C. and in the absence of thecatalyst to merely reduce the number of unsaturated bonds in the dryingoil reactant to a limited degree as determined by the length of time thereaction is allowed to proceed. The product obtained under such partialconditions of reaction is a fluid reaction product which still containsa large number of the unsaturated bonds originally present in the dryingoil. It dries readily on exposure to atmospheric oxygen, but the filmobtained thereby from a modified hydrocarbon drying oil for example,possesses none of the characteristic embrittlement tendencies of theoriginal drying oil selected as starting material. The drying propertiesof the treated oils are not much impaired if the maleic anhydride valueis reduced through the present treatment by about one-fourth, whereas bysuch a reduction the properties of the .dried films are improved, e. g.the hydrocarbon drying oil films are reduced in the brittleness, whilethe frosting drying oil films are of improved clarity. If desired, theinitial product obtained on partial condensation of the olefin anddrying oil or additional fresh drying oil charge may be further reactedwith a further quantity of the mono-olefin reactant either for anextended period of reaction or in the presence of a catalyst and/or athigher temperatures toobtain a more deep-seated alteration in theproperties of the drying oil. If the reaction is allowed to continuefurther, the drying oil may contain few, if any, conjugated unsaturatedbonds or multiple double bond systems capable of conjugation. In thecase of glyceride or other ester-type drying oils, the reaction with theolefin hydrocarbon may be accompanied by polymerization of the oilitself so that a noticeably more viscous product is obtained.

The process may be operated either on a continuous or batchwise basis,but preferably under such conditions that the reactants are intimatelycontacted during the condensation and/ or copolymerization reaction. Ina typical batch operation for example, the drying oil, which may bedissolved in a suitable diluent, is vigorously agitated in the presenceof the olefin reactant under pressure, for example, in a stirredpressure autoclave into which the olefin, if in the gaseous state, isintroduced below the surface of the normally liquid drying oil reactant.In a typical continuous method of operation, the liquid mixture ofdrying oil, diluent, olefin, and catalyst, if present, may be allowed toflow over suitable solid contact material, such as quartz, Berl saddles,etc. at suitable temperature and pressure conditions. The apparatus mayconsist of a tower or a number of towers connected in series ofsufiicient height to provide the desired contact period and containingthe contact material distributed within the column. The tower eflluentmay be further'recycled to effect the desired degree of modification ofthe drying oil.

The catalyst, if utilized in the reaction, may be removed from theproduct by vaporizing the same at an elevated temperature or by awashing or extraction treatment with a solvent capable of dissolving thecatalyst in which the product is relatively insoluble. In manyinstances, especially when the amount of catalyst utilized in thereaction is small, or when an organic catalyst such as a peroxide isutilized, the latter may be simply left in the product without seriouseffect on its drying or other properties.

The present process is illustrated in greater detail in the followingexamples in which specific members of the broadly defined groupshereinabove specified are reacted in accordance with the present processto obtain a modified drying oil product. The examples, however, are notto be construed as limiting the broad scope of the invention inaccordance thereto.

Example I A synthetic hydrocarbon type of drying oil containing amixture of conjunct hydrocarbon polymers was prepared by the followingreaction in which an octene fraction of a copolymer (of propylene andbutylene) gasoline was reacted with hydrogen fluoride to form a sludgephase and a relatively saturated hydrocarbon phase. The sludge phase wasmixed with water to hydrolyze the catalysthydrocarbon complexescontained in the sludge and the hydrocarbons recovered as the synthetichydrocarbon drying oil utilized as charging stock herein. The product asrecovered, however, dries on exposure to atmospheric oxygen to form afilm which is brittle and which has little abrasion resistance. The rawdrying oil product was thereafter reacted with an olefin in accordancewith the present invention to form the modified drying oil product asherein provided.

22 liters (16.5 kg.) of non-selective copolymer of Br No. 162 (polymersof mixed butylenes and propylene referred to as a polymer gasoline)consisting predominantly of mono-olefinic hydrocarbons containing fromabout 8 to about 12 carbon atoms per molecule was charged into anautoclave and rapidly stirred as 9.0 kg. of liquid anhydrous hydrogenfluoride was introduced into the reactor. The pressure was maintainedthroughout the reaction at an average value of about 205 pounds persquare inch by means of compressed nitrogen. The temperature wasincreased to 91 C. and stirring was continued for an additional hour.The reaction mixture separated into two phases on standing: an uppersaturated hydrocarbon layer (bromine number=10) and a lower acidiclayer. The upper layer, after washing with aqueous caustic to remove asmall amount of dissolved hydrogen fluoride, weighed 8.1 kg.

The lower acidic sludge layer weighed 16.1 kg. after removal ofentrained upper layer by extracting the latter with liquid pentane andwas a light brown mobile fluid having a density of 0.98 at 4 C. Itsyield, based on the total charge, was 63 percent.

100 g. of the above hydrogen fluoride sludge was allowed to flow into amixture of ice and water, additional ice being added as the heat ofreaction melted the ice in the hydrolyzing reactor. 43.4 g. of alight-colored, sweetsmelling oil separated from the aqueous phase, ayield of 42.2% based on the original olefin charged and 43.4% based onthe weight of sludge hydrolyzed. An examination of the oil indicated thefollowing properties:

Boiling range 160 to above 400 C. Density, d4 0.863. Refractive index,11 1.4871. Color, Gardner 12-13. Molecular weight, average 263. Dienenumber 85. Bromine number 195. Specific dispersion 143. Percent fluorine0.06. Double bonds/molecule (aver- 3.2.

age).

Although the hydrocarbon drying oil herein described was. prepared froma hydrogen fluoride sludge and was recovered therefrom by an aqueoushydrolysis procedure, a somewhat similar material may be obtained froman aluminum chloride or sulfuric acid sludge, and the conjuncthydrocarbon polymers comprising said drying oil may be also recoveredfrom the hydrogen fluoride sludge by flashing oil? the hydrogenfluoride.

The raw hydrocarbon drying oil as prepared above was modified inaccordance with the present process by reacting the same with ethyleneunder pressure in a thermal type of reaction.

50 grams of the 220325 C. fraction of the raw hydrocarbon drying oilproduct (having a maleic anhydride value of 98) was charged into arotating pressure autoclave and heated with 47 atmospheres pressure ofethylene at a temperature of 120 C. for 4 hours.

The modified drying oil remaining in the autoclave after release ofethylene had a maleic anhydride value of 63 and boiled within thetemperature range of from about 252 to about 331 C.

The product when tested as a drying oil by spreading the same in a thinfilm over test panels and exposing the same to air set in one day to anon-tacky film, dried completely in 6 days, and exhibited considerablyless brittleness than a similar film prepared from the untreated oilfraction.

Example II 40 grams of the hydrocarbon drying oil product prepared as inExample I was charged into a stirred pressure autoclave together withgrams of butene-2. The pressure was increased to 50 atmospheres byintroducing nitrogen into the reactor until the latter pressure wasobtained. The contents were stirred and heated to 170 C. for 6 hours.

The product drying oil had a maleic anhydride value of 65 and dried onexposure to the atmosphere to a nontacky, non-brittle film.

Example Ill Dehydrated castor oil of 19 maleic anhydride value washeated in a bomb for two hours at 140 C. under 40 atmospheres (initial)of ethylene pressure. The product, after degasification, had a maleicanhydride value of 14, and dried in the absence of driers to anon-frosty film in 40 hours. The untreated oil dried in 36 hours to afrosty film.

Example IV A sample of tung oil of 69 maleic anhydride value was treatedas in Example III except that the temperature was maintained at C. Theproduct had a maleic anhydride value of 52, and, like the treateddehydrated castor oil, dried to a clear, non-frosty film.

I claim as my invention:

1. A process for modifying an unsaturated fatty acid compound containingconjugated olefinic unsaturation selected from the group consisting ofthe fatty acids and the fatty acid esters derived from a naturalglyceride drying oil which comprises reacting said compound in theabsence of added catalyst with an aliphatic mono-olefinic hydrocarboncontaining from 2 to 4 carbon atoms at a temperature of from about 50 toabout 300 C.

2. The process of claim 1, further characterized in that the olefinichydrocarbon is ethylene.

3. The process of claim 1, further characterized in that said compoundis tung oil.

4. The process of claim 1, further characterized in that said compoundis dehydrated castor oil.

5. The process of claim 1, further characterized in that said: compoundis a fatty acid ester.

References Cited in the file of this patent UNITED STATES PATENTS2,574,753 Opp et al. Nov. 13, 1951

1. A PROCESS FOR MODIFYING AN UNSATURATED FATTY ACID COMPOUND CONTAININGCONJUGATED OLEFINIC UNSATURATION SELECTED FROM THE GROUP CONSISTING OFFATTY ACIDS AND THE FATTY ACID ESTERS DERIVED FROM A NATURAL GLYCERIDEDRYING OIL WHICH COMPRISES REACTING SAID COMPOUND IN THE ABSENCE OFADDED CATALYST WITH AN ALIPHATIC MONO-OLEFINIC HYDROCARBON CONTAININGFROM 2 TO 4 CARBON ATOMS AT A TEMPERATURE OF FROM ABOUT 50* TO ABOUT300* C.